This invention relates to zoned condensers and more particularly to a zoned condenser for a single casing double exhaust turbine. Large turbine generators often have two or three pressure turbine elements, each with double exhausts. For such units zoned or multiple pressure condensers are commonly used and improve the heat rate for two basic reasons; they provide a lower average back pressure and the condensate leaving the condenser has a higher temperature than single pressure condensers. Back pressure of multi-pressure units is lower because the heat rejection per unit length of condenser is more uniform. Thermodynamically this means that heat is transferred at a lower average temperature difference, that is, more efficiently.
Between 1970 and 1977 over 150 turbine generator units with multiple double flow elements used multi-pressure condensers while no known single element, double flow turbine is known to use a zone or multiple pressure condenser which could improve the heat rate up to about 0.7% if zoned or multi-pressure condensers were utilized on single element units.